Health officials in Sierra Leone have confirmed that an Ebola patient who fled from a hospital in the capital has died after handing herself in.

The 32-year-old hairdresser and her parents, who are suspected to have the virus, have been taken to the east of the country where the only Ebola treatment centres and laboratory are located.

The woman was the first known confirmed Ebola case among residents of the capital city, Freetown.

Her family reportedly stormed the hospital, where she had been admitted, and removed her on Thursday (local time) after she had tested positive to the virus.

Health workers are setting up an Ebola treatment centre in Lakka village, about 20 kilometres south of Freetown, to prepare for future cases near the capital.

Across Guinea, Liberia and Sierra Leone, at least 660 people have died from the illness, according to the World Health Organisation (WHO), placing great strain on the health systems of some of Africa's poorest countries.

The virus is still spreading. A Liberian man who died in Nigeria's commercial capital, Lagos, tested positive for the virus on Friday (local time), Nigeria's health minister said.

Sierra Leone now has the highest number of cases at 454, surpassing neighbouring Guinea where the outbreak originated in February.

Ebola can kill up to 90 per cent of those who catch it, although the fatality rate of the current outbreak is around 60 per cent.

Highly contagious, especially in the late stages, its symptoms include vomiting and diarrhoea as well as internal and external bleeding.

US agencies including from the Center for Disease Control (CDC) have been lending their expertise to local health officials and international specialists.